The present invention relates to electrostatographic reproducing apparatus and more particularly to a novel sheet transport apparatus for use therein. More specifically, the present invention is directed to a jam clearance baffle for use in removing jammed copy sheets from a sheet transport path without the necessity of physical contact between the operator and the affected units.
In electrostatographic reproducing apparatus commonly used today, a photoconductive insulating member is typically charged to a positive potential, thereafter exposed to a light image of an original document to be reproduced. The exposure discharges the photoconductive insulating surface in exposed or background areas and creates an electrostatic latent image on the member which corresponds to the image areas contained within the original document. Subsequently, the electrostatic latent image on the photoconductive insulating surface is made visible by developing the image with a developing powder referred to in the art as toner. During development the toner particles are attracted from the carrier particles by the charge pattern of the image areas on the photoconductive insulating area to form a powder image on the photoconductive area. This image may be subsequently transferred to a support surface such as copy paper to which it may be permanently affixed by heating or by the application of pressure. Following transfer of the toner image to the support surface the photoconductive insulating surface may be discharged and cleaned of residual toner to prepare for the next imaging cycle.
One of the difficulties frequently encountered in an automatic reproducing apparatus has to do with the occurrence of paper jams at virtually any point in the copy sheet path. The paper jams are caused as a result of paper trying to negotiate curves and baffles or the paper itself having torn edges, dog ears or being curled. The defects in the individual copy sheets could of course cause a paper jam in any place in the paper path in the machine. Frequently paper jams take place adjacent to major operational stations in the machine wherein significant operations are performed on the paper. For example, jams can take place at the entrance to the transfer station where the copy sheet is brought into contact with the photoreceptor for the transfer of the toner image to the photoreceptor. Similarily the difficulties may occur at the fixing station wherein the toner image on the copy sheet is fixed onto the copy paper. In the instance where the copy sheet is brought into contact with the photoreceptor which typically is in the form of a rotatably cylindrical drum or a reusable belt, the leading edge of the copy sheet is tacked to the photoreceptor in registration with the leading edge of the toner image on the drum. If a paper jam occurs, the operator may remove a cover of the machine and manually reach in and attempt to withdraw or extract the paper from the jammed condition. In the process of trying to withdraw or extract the copy sheet from the jammed position, the possibility of damaging the photoreceptor is greatly increased. For example, the photoreceptor can be damaged by being contacted with fingernails of the operator, which can scratch the photoreceptor surface which ultimately may affect the electrical properties providing non-uniform charging of the photoreceptor on subsequent imaging cycles. Furthermore it is possible that fingerprints may also be placed on the photoreceptor which can also result in cyclical imaging problems. With respect to difficulties encountered with the fixing device, which typically involves hot surfaces such as a radiant fuser or heated roll fuser, the manual extraction of a jammed copy sheet increases the possibility of the operator being burned by contact with a heated surface.
Typically in the prior art, it has been the practice to have either the upper or the lower transports of the paper path movable out of the paper path so that the copy sheet could be physically, manually extracted by the operator. As noted previously, while the jammed copy sheet can be manually extracted, this creates the possibility of damage to either operational portions of the machine or to the operator extracting the jammed copy sheet. Thus, for example, in the copy sheet sorter associated with the 7700, the top transport of the sorter module is pivotably opened so that the copy sheets can be manually extracted.